The present invention relates to motor operator mechanisms having specific, but not necessarily limited application to industrial circuit breakers. More particularly, the present invention relates to variable drive coupling apparatus capable of quickly bringing the deactivated motor operator mechanism to a stop while being effectively drivingly decoupled from the circuit breaker or other instrumentality. Moreover, the present invention is an improvement over the variable drive coupling link assembly of commonly assigned, copending E. H. Rask application Ser. No. 051,587, filed June 25, 1979, now Pat. No. 4,234,772, the disclosure of which is incorporated herein by reference.
In their application to circuit breakers, motor operator mechanisms are utilized in lieu of manual means, such as an operating handle, to charge the breaker's spring powered contact operating mechanism preparatory to contact reclosure after the breaker has been tripped open. Typically, the motion of the motor operator mechanism must be rather precisely tailored to a particular breaker's contact operating mechanism. This is particularly so with regard to the start and stop positions of the motor operator mechanism. Typically, these start and stop positions are virtually one in the same, termed a "home" position. Under these circumstances, it is essential that the motor operator mechanism stop rather precisely in its home position at the conclusion of a charging cycle in order that it be in the proper position to start the next charging cycle. To achieve this, prior art motor operator mechanisms have utilized braking techniques, either mechanical braking or both, which are effectuated essentially coincidentally with motor de-energization as the motor operator mechanism arrives at its home position. While these braking techniques are generally effective in abruptly stopping a motor operator mechanism within acceptable limits of its home position, they do indeed add cost and complexity to the motor operator mechanism. Moreover, any braking technique poses potential field service problems.
It is accordingly an object of the present invention to provide an improved apparatus for variably drivingly coupling a motor operator mechanism with an operator member of an instrumentality.
A further object is to provide variable drive coupling apparatus of the above character operating to decouple the motor operator mechanism from the operator member at the conclusion of an operating cycle and thus eliminate the need to abruptly stop motor operator mechanism at a predetermined position.
Another object is to provide variable drive coupling apparatus of the above character operating to automatically establish a resilient lost motion coupling between the motor operator mechanism and the operator member at the conclusion of each operating cycle and thereby effectuate a braking zone during which the deactivated motor operator mechanism is brought to a stop without disturbing the position of the operator member.
Still another object is to provide variable drive coupling apparatus of the above character wherein, during the braking zone, the operator member is latched in its home position while the kinetic energy of the deactivated motor operator mechanism is absorbed, and wherein at the conclusion of the braking zone the operator member is unlatched from its home position and the absorbed kinetic energy is then discharged to propel the operator member into an operating cycle.
Yet another object is to provide variable drive coupling apparatus of the above character operating to automatically compensate for the effects of the lost motion connection during each operating cycle and thus achieve uniformity of operator member movement.
A further object is to provide variable drive coupling apparatus of the above character which is efficient in design and reliable in operation.
Other objects of the invention will in part be obvious and in part appear hereinafter.